PFC3D Simulation Study Considering Spherical Particle Cementation

Cementation characteristic plays an important role in the soil structure and it has always been one of the hot topics studied for geotechnical scholars.At preseat,tests can not reveal the effect of cementation on the macroscopic mechanical properties of soil from a mesoscopic pointof view and PFC,as a discrete element method,is an effective microanalysis tool.This paper is based on the results of existing spherical particle cementation tests and uses PFC3D particle flow software for numerical simulation studies.The numerical simulation process is divided into three steps:establish a numerical model oonsistent with the test data,analyze the changes of the internal field of the model from a microscopic point of view and analyze the effect of mesoscopic parameters an the macro-mechanical characteristics of the model.The specific research work is as follows:1.The models are based on the existing spherical particle cementation test results and combined with the characteristics of the particle software.tbe size,porosity,and particle density of the model are determined.By calibrating the mesoscopic paramenters the model,the PFC3D three-axis numerical models under different wax and bentonite ratios arc established.This paper also analyzes the similarities and differences between the stress-stain relationship and the peak strength obtained from the models and the tests,and anlyzes the reasons.By analyzing p-q critical state lines of models and tests,their corresponding cohesion and internal friction angle can be obtained.The rationality of the established model is further illustrated by comparing the cohesion and the internal friction angle.2.Based on the establishment of models under different wax and bentonite ratios,the changes of the velocity field,displacement field,contact force chain,and parallel bond bond position in the interior of the model(profile layer and center layer)under different strains are analyzed from the microscopic point of view and combined with the macro-mechanical characteristics of the model for analysis,which explores the impact of microscopic changes on macroscopic mechanical properties.3.The paper selecte the mesoscopic parameter of the model calibration with the ratio of wax and bentonite of 2:1 as the initial value,and studies the effect of different loading rates,particle friction coefficients,parallel bond radius factors,parallel bond normal stiffnesses,parallel bond tangential stiffnesses,parallel bond normal strengths and parallel bond tangential strengths on the macro-mechanical properties of the model.Meanwhile,the effect of each mesoscopic parameter on the peak strength,residual strength,strain softening and hardening and initial elastic modulus of the stress-strain curve are summarized in detail.